It was the first time a politician or any government representative had referred to a total number of fatalities in the drone strikes, which have been condemned by rights groups as extrajudicial assassinations.

The toll from hundreds of drone-launched missile strikes against suspected Al-Qaeda militants in Pakistan, Yemen and elsewhere has remained a mystery, as US officials refuse to publicly discuss any details of the covert campaign.

But Republican Senator Lindsey Graham, a staunch supporter of the drone raids, openly cited a number that exceeds some independent estimates of the death toll.

“We’ve killed 4,700,” Mr Graham was quoted as saying by the Easley Patch, a local website covering the small town of Easley in South Carolina.